Hey Jiri
I forgot to put you on CC on the initial patch. Any comments on this?
Cheers
David
On Mon, Sep 9, 2013 at 6:51 PM, Tom Gundersen <teg@xxxxxxx> wrote:
> On Mon, Sep 9, 2013 at 6:33 PM, David Herrmann <dh.herrmann@xxxxxxxxx> wrote:
>> udev has this nice feature of creating "dead" /dev/<node> device-nodes if
>> it finds a devnode:<node> modalias. Once the node is accessed, the kernel
>> automatically loads the module that provides the node. However, this
>> requires udev to know the major:minor code to use for the node. This
>> feature was introduced by:
>>
>> commit 578454ff7eab61d13a26b568f99a89a2c9edc881
>> Author: Kay Sievers <kay.sievers@xxxxxxxx>
>> Date: Thu May 20 18:07:20 2010 +0200
>>
>> driver core: add devname module aliases to allow module on-demand auto-loading
>>
>> However, uhid uses dynamic minor numbers so this doesn't actually work. We
>> need to load uhid to know which minor it's going to use.
>>
>> Hence, allocate a static minor (just like uinput does) and we're good
>> to go.
>>
>> Reported-by: Tom Gundersen <teg@xxxxxxx>
>
> Thanks, this works (I only tested the creation of the device node, not
> the actual module loading).
>
>> Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
>> ---
>> drivers/hid/uhid.c | 3 ++-
>> include/linux/miscdevice.h | 1 +
>> 2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
>> index 5bf2fb7..93b00d7 100644
>> --- a/drivers/hid/uhid.c
>> +++ b/drivers/hid/uhid.c
>> @@ -615,7 +615,7 @@ static const struct file_operations uhid_fops = {
>>
>> static struct miscdevice uhid_misc = {
>> .fops = &uhid_fops,
>> - .minor = MISC_DYNAMIC_MINOR,
>> + .minor = UHID_MINOR,
>> .name = UHID_NAME,
>> };
>>
>> @@ -634,4 +634,5 @@ module_exit(uhid_exit);
>> MODULE_LICENSE("GPL");
>> MODULE_AUTHOR("David Herrmann <dh.herrmann@xxxxxxxxx>");
>> MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
>> +MODULE_ALIAS_MISCDEV(UHID_MINOR);
>> MODULE_ALIAS("devname:" UHID_NAME);
>> diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h
>> index 09c2300..cb35835 100644
>> --- a/include/linux/miscdevice.h
>> +++ b/include/linux/miscdevice.h
>> @@ -45,6 +45,7 @@
>> #define MAPPER_CTRL_MINOR 236
>> #define LOOP_CTRL_MINOR 237
>> #define VHOST_NET_MINOR 238
>> +#define UHID_MINOR 239
>> #define MISC_DYNAMIC_MINOR 255
>>
>> struct device;
>> --
>> 1.8.4
>>
--
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